Problem: $ { \left[\begin{array}{rr}{1} & {-2} \\ {1} & {2} \\ {0} & {-1}\end{array}\right]-\left[\begin{array}{rr}{2} & {1} \\ {-2} & {2} \\ {4} & {3}\end{array}\right] = {?} } $
To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{1}-{2} & {-2}-{1} \\ {1}-{-2} & {2}-{2} \\ {0}-{4} & {-1}-{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-1} & {-3} \\ {3} & {0} \\ {-4} & {-4}\end{array}\right]}$